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Full Discussion: C first Script Question
Top Forums Programming C first Script Question Post 302751799 by Corona688 on Friday 4th of January 2013 01:13:30 PM
Old 01-04-2013
scanf() has an unfortunate problem where, if it finds any bad data in the stream, it puts it back. You are asking for %d, so it looks for digits. If it sees any non-digits, it will give up and not even show them to you.

Imagine you're trying to read 9 numbers with 9 scanf calls, and on the very first one you type in A then enter. The first scanf will see 'A', decide it's not a number, and put it back. This means the second will also see 'A'. So will the third, fourth, fifth, sixth, seventh, eighth, and ninth.

sscanf, which operates on strings instead of streams, avoids this problem, since it has nowhere to "put back" the letter into. It just uses the string you give it and doesn't care what happened last time. fgets() and sscanf() make a good team; fgets reads entire lines and turns them into strings, while sscanf() processes strings and turns them into what you want.

Code:
while(fgets(buf, 512, stdin) != NULL)
{
        int value;
        if(sscanf(buf, "%d", &value) == 1)
        {
                printf("You typed a number\n");
        }
        else
        {
                printf("You didn't type a number\n");
        }
}

Note that this will accept things like 1234a, since sscanf will stop at the a.
Last edited by Corona688; 01-04-2013 at 02:18 PM..
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LEARN ABOUT DEBIAN

rt-shredder-4

rt-shredder(8)						     Request Tracker Reference						    rt-shredder(8)

NAME

       rt-shredder - Script which wipes out tickets from RT DB

SYNOPSIS

	 rt-shredder --plugin list
	 rt-shredder --plugin help-Tickets
	 rt-shredder --plugin 'Tickets=query,Queue="general" and Status="deleted"'

	 rt-shredder --sqldump unshred.sql --plugin ...
	 rt-shredder --force --plugin ...

DESCRIPTION

       rt-shredder - is script that allow you to wipe out objects from RT DB. This script uses API that RT::Shredder module adds to RT.  Script
       can be used as example of usage of the shredder API.

USAGE

       You can use several options to control which objects script should wipeout.

OPTIONS

   --sqldump <filename>
       Outputs INSERT queries into file. This dump can be used to restore data after wiping out.

       By default creates files <RT_home>/var/data/RT-Shredder/<ISO_date>-XXXX.sql

   --object (DEPRECATED)
       Option has been deprecated, use plugin "Objects" instead.

   --plugin '<plugin name>[=<arg>,<val>[;<arg>,<val>]...]'
       You can use plugins to select RT objects with various conditions.  See also --plugin list and --plugin help options.

   --plugin list
       Output list of the available plugins.

   --plugin help-<plugin name>
       Outputs help for specified plugin.

   --force
       Script doesn't ask any questions.

SEE ALSO

       RT::Shredder

perl v5.14.2							    2013-05-22							    rt-shredder(8)
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